On the morphological variations of geographically isolated migratory and non-migratory populations of Tropical shad, Tenualosa ilisha (Hamilton, 1822) from three distinct tropical ecosystems.

Abstract

The migratory tropical shad, Tenualosa ilisha has a wide range of habitat preferences like rivers, reservoirs, estuaries, backwaters, and coastal waters during different phases of its life cycle. The present study investigates morphological variations among three populations of Hilsa from distinct ecosystems such as the River Brahmaputra, Narmada estuary and Ukai reservoir. Thirteen morphometric and nine meristic measurements were considered for the present study. Among the meristic traits, significant variation was observed in counts of lateral line scales and post ventral scutes. The MANOVA results depict a significant difference in the morphometric traits among the three populations. The factor analysis indicated a very significant loading of head-related traits on the first factor and traits related to the middle and caudal region on the second factor. The study portrayed a significant morphological variation among the different stocks of T. ilisha and the results were confirmed in discriminant function analysis.